Anyone who knows me will tell you that I’m not one to seek out a physical challenge. For me, the plank is something pirates used in days gone by and dips are something my wife and I put out when friends come over.

Now all that has changed. I have a pair of walking boots, an app on my phone which counts my steps and last week I attended my first Pilates class. Why? Because the unthinkable has happened and I have volunteered to take part in Camp Simcha’s second overseas challenge, The Coastal Freedom Trail.

From July 16 to 21, I will be joining other Camp Simcha fundraisers to walk the 72km route across the Pyrenees, used by men, women and children attempting to flee the Nazis during the Second World War.

Over the past 12 years as chief executive of Camp Simcha, I have supported, thanked and applauded the hundreds of people who have undertaken physical challenges to raise money for our work supporting families coping with serious childhood illness. I have never undertaken one myself but this challenge struck a chord with me. It was the escape route my wife’s father successfully took, aged just 14 in 1942.

My father-in-law Joseph Sagal was born to Polish parents, in Cologne in 1928. In October 1938, when the Germans were expelling all the Polish Jews, Joseph’s father, under the guise of doing business in Paris, put Joseph and his older brother Max on his passport and got the boys out. Their mother was left behind, unable to join them for another four years.

After four years in Paris, as life there became more perilous, the boys were sent to a safer place in Moissac with the French Jewish scouts. It was here that Joseph had his barmitzvah without his parents — Max taught him how to leyn.

After Joseph and Max’s mother had made it to France, the family moved to Luchon in the Pyrenees, where they lived for about a year. Joseph told us he had given a bottle of wine to the commandant who lived on the first floor of their apartment building and it was this same commandant who one night warned Joseph’s parents that they had to leave France immediately. The next morning would be too late.

With a group of 10 people and a guide, they left that night to walk over the Pyrenees to Spain — a similar route to the one I will be taking in July.

They all walked across the Pyrenees, dodging the Germans and their dogs but, as they came down the mountain in Spain, the Spanish police were waiting for them, with orders to transfer them back to France that day with potentially dire consequences. Detained at the police station, the group decided to escape by jumping out of a top floor window and agreed to meet up at a hut they could see in the mountains. Joseph and his father jumped last — forced to leave an elderly woman who couldn’t do it. My father-in-law told us he was always haunted by the image of her standing by the window as they went.

When they reached the hut, Joseph’s mother was missing. Joseph’s father was about to give himself up when they saw a stranger on the mountain. Joseph told them what had happened and amazingly, the man, who had fought against Franco in the Spanish Civil War, risked his life to get Joseph’s mother. He found her and the family made their escape towards Barcelona.

Once there, the American Jewish Joint Distribution Committee looked after them. Joseph’s mother had a sister in England so he and Max left their parents in Barcelona to travel to Lisbon and then on to the UK. Just after they boarded their plane bound for England, a steward came and told them they would have to take the next plane because their seats were being taken by a VIP. That same plane, which they had to vacate, was shot down by the Germans — with no survivors.

Joseph and Max made it safely to the UK and their parents followed later. Half a century later, in 2007, Joseph and his wife Beryl retraced his journey over the Pyrenees, with my wife Roz and her sisters. Recalling that terrible time was very emotional for him: he told me he thanked God he was able to make that same journey with his own family, in such peaceful circumstances all those years later.

Without his bravery, my life would not be the same today. I thank him for my family and I honour him by retracing his footsteps for the benefit of other families trying to navigate their way out of their own terrible times.

Sadly, my father-in-law passed away three years ago, but his bravery and endurance in the most extreme and gravest of circumstances has inspired me to do this challenge in his memory.

It seems fitting that it will raise money to support Camp Simcha families with seriously ill children, who also endure so much and inspire us all with their bravery in the toughest of circumstances.

You can sponsor Neville at www.justgiving.com/fundraising/NevilleGoldschneider. If you are interested in taking part in the Camp Simcha Freedom Trail Challenge email sarahj@campsimcha.org.uk